In a liquid material discharge device, when a liquid material 18 is continuously discharged, there often occurs a phenomenon (see FIG. 11), called “creeping and climbing”, that the surplus liquid material 18 adheres to nozzle outer surfaces, such as a distal end surface and an outer lateral surface of a discharge tube 57 of a nozzle 56 due to the influences of surface tension, etc. The occurrence of the “creeping and climbing” causes a problem that, due to the influences of the liquid material 18 adhered to the outer surfaces of the nozzle 56 (particularly, the distal end surface of the discharge tube 57), variations generate in a discharge rate, or the discharged liquid material 18 has a shape different from the intended one (for example, the intended circular shape is deformed to an elliptic or another distorted shape).
Particularly, in a discharge device of the type that the liquid material departs from a nozzle before reaching a coating object (hereinafter referred to as the “flying discharge type”), there occurs, in addition to the above-described problem, an another problem that the liquid material does not depart from the nozzle and does not reach the coating object, or that a flying direction bends. The liquid material remaining adhered to the nozzle may further adversely affect the discharge, or may no longer stay there with increasing weight and may adhere to an unexpected position of the coating object, thus making the problem more serious.
In view of the problems described above, various techniques for avoiding the “creeping and climbing” of the liquid material and keeping the nozzle in a clean state have been proposed so far.
Patent Document 1 discloses a wiping device including a pair of wiping rollers that are rotated in opposite directions with a tip of a coating nozzle inserted between the pair of wiping rollers, and a pitch feed device that moves the wiping rollers through a certain distance in an axial direction, wherein, after moving the nozzle to a position above the wiping device, the nozzle is descended until it is inserted between the wiping rollers, and a motor is rotated while the nozzle is kept in a descended state, such that the rollers wipe off an adhesive, etc. remaining on outer surfaces of the nozzle.
Patent Document 2 discloses a device including scraping means provided with a scraping member that has a length spanning over a tip opening of a discharge nozzle, and with a reciprocating mechanism that reciprocally moves the scraping member in a direction perpendicular to a discharge direction in a state of the scraping member being in contact with the tip opening of the discharge nozzle, wherein, after a flowing material has been coated on a coating object member and when the flowing material is in a state projecting from the tip opening of the discharge nozzle, a scraping step is performed to scrape off the remaining flowing material.
Patent Document 3 discloses a nozzle cleaner including an inverted conical recess into which a nozzle tip is removably inserted, a cylindrical cleaning hole extending from a lower end opening of the recess exactly downwards and allowing the nozzle tip to be inserted into the cleaning hole, an air supply path having a blow opening between the recess and the cleaning hole, and ejecting compressed air therethrough, and an air suction path communicating with the cleaning hole and allowing the compressed air and a blown-off paste material to be expelled out under suction therethrough, wherein a nozzle is inserted into both the recess and the cleaning hole, and the compressed air is ejected from the blow opening such that the paste material adhered to a lower end portion of the nozzle is blown off and expelled out under suction through the air suction path.
Patent Document 4 discloses a device including a cleaning chamber that has a funnel portion, first solvent supply means for supplying a solvent to the funnel portion, second solvent supply means for supplying a solvent to an upper side of the funnel portion, and nozzle suction means, wherein when a nozzle is positioned in the cleaning chamber, the surface of a treatment liquid in the nozzle is retracted by the suction means, the solvent is supplied from the first solvent supply means to form a vortex flow of the solvent and to clean the nozzle, the solvent is supplied from the second solvent supply means to form a liquid pool within the cleaning chamber, and the suction means performs suction to form a treatment liquid layer, an air layer, and a solvent layer inside a nozzle tip.